If you’ve integrated GSuite email with your domain name, you will not be able to receive emails in your cPanel webmail accounts. Hence, any email sent to any email account that is not created in gsuite (even if created in cPanel) will bounce by default.
With gsuite routing, you can now set up your gsuite email as destination for emails sent to your domain unknown email accounts i.e you can configure email forwarding or email filters at gsuite to forward all unrouted emails to your main gsuite email address.
I’ve set it up for my domain via my gsuite settings ( Advanced settings > routing) and it’s working perfectly.
So, if you send email to whatever@ogbongeblog.com, I will receive it in my main email address. 
See the official guide here. >> “Set up a catch-all address”.